1. Field
Embodiments of the invention relate to a jib assembly that is the projecting arm of a crane or the like. More particularly, embodiments of the invention relate to a sliding lock mechanism for securing the jib assembly in a desired position.
2. Related Art
A jib assembly broadly comprises a jib arm extending from a support base. The jib assembly bears a load or an item of equipment. The jib arm may be telescoping to extend or retract into itself or into the base. The jib arm may rotate around the base in either or both of vertical and horizontal positions. The base itself may be movable relative to a larger item of equipment, such as a crane or a boom of an aerial device. In some embodiments, the jib assembly may be mounted at a distal end of the crane or the boom. The combination of these movements allows the jib arm to move the load or item of equipment into a desired location or orientation.
Jib assemblies are frequently mounted on construction equipment, such as the above-mentioned cranes, excavators, digger derricks, and utility trucks. Jib assemblies are also commonly used for video cameras, because they facilitate shots not possible to a person holding a video camera, such as sweeping shots and high angle shots. Jib assemblies may also be employed for moving equipment into and out of a truck bed.
In more detail, jib assemblies generally comprise a base, an outer boom coupled to the base, and a jib arm at least partially telescopically received within the outer boom. The jib arm is extended by moving a section of the jib arm external to the outer boom. Other jib assembly embodiments may comprise a base and a jib arm. In such a jib assembly, the jib arm extends and retracts relative to the base.
Power sources to extend and retract the jib assemblies include hydraulics, pneumatics, electric power, and manual force. Once in a desired position, the jib assemblies typically use at least one pin to secure the jib arm in place. The pins are emplaced into an opening in both the jib arm and the outer boom. The pins prevent the jib arm from extending or retracting once set. When the operator desires to alter the jib arm's position, he removes the pins, moves the jib arm in or out to the desired position, and reinserts the pins.
There are several drawbacks to this configuration. First, the pins can be difficult to reach, as they are typically on only one side of the jib assembly. Second, the pins can be difficult to insert into and remove from the openings in the jib arm because of binding. Third, this configuration requires precise alignment of the interior and outer booms of the jib assembly. Fourth, the operator is limited in what position he can extend or retract the jib arm, because it must align with the limited number of holes in the jib arm. Fifth, the pins can wear out and break under the pressures resulting from the load on the jib assembly. Finally, an operator can forget to re-engage the pins, resulting in an unsafe operating environment.